Whole U.S. Eastern Interconnection FRCC

Peak 

Coincident 

Load 

Day

High

Solar

Generation

Day

The information contained in this poster is subject to a government license.

Solar Power International

Chicago, Illinois

October 21–24, 2013

NREL/PO-5D00-60241

This work was supported by the U.S. Department of Energy under Contract No. DE-AC36-08GO28308

with the National Renewable Energy Laboratory. 

NREL is a national laboratory of the U. S. Department of Energy, Office of Energy Efficiency

and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Eastern Renewable Generation Integration Study: Initial Results

Aaron Bloom, Aaron Townsend, Marissa Hummon, Andrew Weekley, Kara Clark, NREL

Jack King, RePPAE, LLC 

The Eastern Renewable Generation Integration Study (ERGIS) aims to answer critical questions about the 

future of the Eastern Interconnection (EI) under high levels of solar and wind penetration. The study is 

developing a robust production cost simulation database with detailed subhourly data on solar, wind, and 

thermal plants, and load. ERGIS uses an advanced production-cost model (PLEXOS) at a subhourly time 

resolution to understand the impact of 30% solar and wind penetration on ancillary services, interchange, 

and net load. ERGIS will address the following questions:

• What does the variability and uncertainty of net load look like under high penetrations of solar and wind 

power? 

• How could unit commitment and dispatch change under high penetrations of renewables?

• Are there any operational strategies that could be used to minimize the cost of integrating high 

penetrations of solar and wind?

• What are the regional impacts of high solar and wind penetrations?

ERGIS scenarios include up to 10% solar penetration in the EI and up to 30% solar penetration in certain 

regions of the EI. These penetrations require subhourly solar generation profiles for a large amount of 

installed solar capacity in the EI, which did not previously exist. ERGIS uses a method previously 

developed at NREL to create realistic solar power profiles from satellite images. The key characteristics for 

the solar data set are: 

• Appropriate number and size of ramps at each location

• Appropriate coincidence of ramps at closely clustered locations

• Appropriate ramps in the sum of solar power throughout a region

About the Study 

Technical Review Committee

NREL worked with the Department of Energy to bring together industry experts for a technical review 

committee to aid in the development of necessary data sets and analyze results as they become available. 

In 2013, the committee oversaw the development of several aspects of the project, including:

• Scenario Development

• Thermal Fleet Expansion

• Transmission Expansion

• Solar Profile Development

• Canadian System Modeling

Energy

Penetration (%)

Solar PV 

Capacity (GW)

Wind 

Capacity (GW)

Conventional

Capacity (GW)

Scenario Solar Wind Rooftop Utility Onshore Offshore Nuclear Coal CC

CT & 

Boiler

Low Renewables 0 3 1 0 30 0 88 231 147 194

State RPS 0.2 12 3 2 91 15 88 230 144 197

Regional 30% 10 20 96 123 168 46 88 212 133 173

National 30% 5 25 50 123 237 27 88 216 137 178

Figure 1: This map shows the assumed structure of the EI in the study year. The pie chart slices indicate the 

relative amount of solar, wind, and other generation in each region, and the relative size of the pie charts 

indicates the amount of generation in each region for the Regional 30% Scenario.

Scenarios

Solar Profile Development

Figure 2: The solar profile development algorithm produces statistically probable correlations between 

solar sites at different locations and under different time scales.

Figure 3: These graphs show normalized solar and wind generation and net load shapes for (left) the entire 

U.S. EI and (right) FRCC for (top) the peak coincident load day and (bottom) a high solar generation day. 

Operating the conventional generators to meet the net load for the whole EI appears reasonable, but certain 

regions could have challenging issues that would likely require operational changes from current practices, 

as illustrated by the large ramps in the FRCC net load.

ERGIS is considering four scenarios designed to evaluate the impact of different solar and wind 

penetrations. The scenarios represent current-day levels, future levels dictated by current state renewable 

portfolio standards (RPS), and high (30%) penetrations of solar and wind. The National 30% Scenario 

requires the U.S. portion of the EI to serve 30% of its annual load with solar and wind, using the best solar 

and wind resources in the EI. The Regional 30% Scenario requires each individual region to serve 30% of its 

annual load with solar and wind within its geographic boundaries, with the exception of SERC, which is 

allowed to import part of its requirement from SPP.

Operational Impacts

ERGIS will evaluate the effectiveness of different operational strategies that could be used to minimize the 

cost of integrating high penetrations of solar and wind, such as:

• New or modified ancillary services products

• Increased sharing of ancillary services between regions

• Faster unit commitment and dispatch cycles

• More frequent interchange scheduling